move versions.json to the plugins dir

[johnsmyth]

Is your feature request related to a problem? Please describe.
Espeially when running in docker: the $INSTALL_DIR/internal/ directory must always be read/write, but you may want the steampipe, postgres, and plugin binaries to be installed in the container image, and/or read only. Because the versions.json is tied to the installation of the plugins, it makes sense to store it with them (otherwise the versions.json may not match the installed plugins)

Describe the solution you'd like
move versions.json from $INSTALL_DIR/internal/ to $INSTALL_DIR/plugins/

[binaek]

@johnsmyth the versions.json file also stores the installation details of the service and the fdw which are installed from the registry.

Should we try to move those details onto a separate file?

[johnsmyth]

@binaek89 perhaps we should consolidate the service and fdw installation data with the data in the signature file ~/.steampipe/db/12.1.0/postgres/signature, and separate out the plugin versions, so we would have some like ~/.steampipe/plugins/plugin-versions.json and ~/.steampipe/db/12.1.0/postgres/db-versions.json, and the db-versions.json would contain the db and fdw info that is currently in the signature file AND the version flie?